This is not what I have in the car now but what was in it when I bought it. I am trying to see if it was a correct date code / #'s matching motor.
Here's what I found so far:

Block casting #: 3969854, casting date: F 28 9 (I believe this makes it a June 28 69, 69-70 2-bolt main block)
Heads: both are 3964290, G 7 9 & G 29 9 (July 7 69 & July 29 69)
Intake: 3931067 D 17 9 ( I believe this means 325hp L-35 engine from April 17 69)

I got this info from moretec.com and yearone.com but I can't seem to decode the engine stamp:

TO73ICJK, my closest guess : T-Tonawanda, CJK or JK-402ci with TH tranny.

Any additional info is greatly appreciated.

Jim A.
http://www.mikesautoclinic.net/69chevelle

That's what I get, 402 (L34) w/TH400 and an assembly date of July 31. The 3-letter suffix was used on 69 402 engines while a 2-letter suffix was a 396.

Have you checked on the rear of the engine above the oil filter for the partial VIN stamped vertically in the rough casting?

That's where my VIN is stamped although it's a 350 horse built earlier in the model year which makes it a 396 with the two character suffix (T0203JE)

Any idea what the I is for? It's definitely an I and not a 1.

Actually the (I) was sometimes used as a (1),either by mistake,or if there were several (1's) in the code, the (I) was used on purpose as a (1).....In your case it's .....(T 07 31 C J K )........July 31 .........

Any idea what the I is for? It's definitely an I and not a 1.

As I recall, the Tonowanda engine plant always used an I instead of 1, and the Flint engine plant used either.
Bruce

Thanks Dale, Dean, mr, and AZCamino for helping me clear this up.